Photocathode material and preparation method thereof, photocathode and application thereof, and preparation method of ethylene glycol

Abstract

The invention relates to the field of ethylene glycol, and discloses a photocathode material and a preparation method thereof, a photocathode and application thereof, and a preparation method of ethylene glycol. The photocathode material is prepared from polydopamine, amorphous carbon and CdIn2S4; the weight ratio of the polydopamine to the amorphous carbon to the CdIn2S4 is 1 to (2 to 5) to (5 to 30). The photocathode material provided by the invention comprises polydopamine, amorphous carbon and CdIn2S4, so that the photocathode material has good light absorption performance and carbon dioxide reduction catalysis capability, and has high selectivity to ethylene glycol; according to the preparation method of the photocathode material, the operation conditions and the technological process are simplified, and industrial production is facilitated; the photocathode material provided by the invention is used for preparing ethylene glycol, and has high selectivity and product quantity.

Description

Technical Field

[0001] The invention relates to the field of ethylene glycol, and in particular to a photocathode material and a preparation method thereof, a photocathode and an application thereof, and a preparation method of ethylene glycol. Background Art

[0002] With the rapid development of industrialization and modernization, the emission of carbon dioxide (CO2) has increased year by year. As the main component of greenhouse gases, CO2 has caused global warming and frequent extreme weather, which has seriously affected people's lives. As a widely distributed, abundant, environmentally friendly, green and sustainable energy source, solar energy has been valued by countries around the world. Using solar energy as a driving force to convert CO2 and water into organic matter is a green chemical technology that people have long dreamed of. It is a necessary technology to achieve the grand goal of carbon neutrality. At present, the research on the catalytic reduction of carbon dioxide in water is mainly electrocatalysis, photocatalysis and photoelectric combined catalysis. The reduction products are mainly formic acid, carbon monoxide, methane, and other small molecular organic substances. Most of the products reported so far have poor selectivity and low yield, and there are still certain difficulties in their application in actual industrial production.

[0003] CN106757136A discloses a method for preparing methanol from carbon dioxide and water. The method can directly obtain methanol from water and carbon dioxide under light conditions with high selectivity. However, it is limited by the FTO glass electrode and has limited application prospects.

[0004] CN105332002A discloses a method for preparing ethanol from carbon dioxide and water. This method can directly obtain ethanol from water and carbon dioxide under light conditions, and has high selectivity. However, it is limited by FTO glass electrodes and has limited application prospects.

[0005] CN109234758A discloses a method for preparing a long carbon chain oxygen-containing compound using carbon dioxide and water. The method can prepare a long carbon chain oxygen-containing compound with a carbon content of about C 50 -C 300 , a series of downstream products are prepared through the cracking process and converted into various required high-value-added chemicals such as alkanes, olefins, gasoline and diesel, which is of great significance, but the reported product structure is unclear.

[0006] Ethylene glycol has a wide range of uses, mainly as a raw material for polyester and in antifreeze. Its synthesis methods are mainly ethylene hydration and ethylene oxide hydration. The ethylene hydration method requires high temperature and high pressure conditions, which consumes a lot of energy; ethylene oxide is prepared by oxidizing ethylene at 120 degrees in air under silver catalysis, which is costly.

[0007] Therefore, there is an urgent need to develop new photocathode materials for use in the preparation of ethylene glycol. Summary of the invention

[0008] The purpose of the present invention is to overcome the problems of the prior art in that the method for preparing ethylene glycol is complex, energy-intensive, poor in selectivity and low in yield, and to provide a photocathode material and a preparation method thereof, a photocathode and its application, and a method for preparing ethylene glycol.

[0009] In order to achieve the above object, the first aspect of the present invention provides a photocathode material, characterized in that the photocathode material comprises polydopamine, amorphous carbon and CdIn2S4;

[0010] The weight ratio of the polydopamine, amorphous carbon and CdIn2S4 is 1:(2-5):(5-30).

[0011] A second aspect of the present invention provides a method for preparing a photocathode material, wherein the method comprises the following steps:

[0012] 1) dispersing silica nanospheres and dopamine in a buffer solution for a first reaction to obtain polydopamine / silica nanospheres;

[0013] 2) annealing the polydopamine / silicon dioxide nanospheres under a protective atmosphere to obtain a sample N / C-SiO2-T;

[0014] 3) The N / C-SiO2-T is uniformly dispersed in ethylene glycol, and InCl3, CdCl2·2H2O and L-cysteine ​​are added in sequence under stirring to carry out a second reaction to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T;

[0015] 4) The CdIn2S4-N / C-SiO2-2-T solid nanospheres are subjected to a third reaction with an HF aqueous solution to obtain hollow nanospheres CdIn2S4-N / C-2-T.

[0016] A third aspect of the present invention provides a photocathode, wherein the photocathode comprises the photocathode material according to claim 1 or a photocathode material prepared by the preparation method according to any one of claims 2-6.

[0017] A fourth aspect of the present invention provides use of the above-mentioned photocathode in the preparation of ethylene glycol.

[0018] A fifth aspect of the present invention provides a method for preparing ethylene glycol, wherein the method comprises:

[0019] Under light conditions, CO2 is introduced into an electrolytic cell for reaction to obtain ethylene glycol; wherein the photocathode in the electrolytic cell is the photocathode as described in claim 7.

[0020] Through the above technical scheme, the photocathode and its preparation method and application and the preparation method of ethylene glycol provided by the present invention achieve the following beneficial effects:

[0021] (1) The photocathode material provided by the present invention includes polydopamine, amorphous carbon and CdIn2S4, so that the photocathode material has good light absorption performance and catalytic carbon dioxide reduction ability, and has high selectivity for ethylene glycol;

[0022] (2) The preparation method of the photocathode material provided by the present invention simplifies the operating conditions and process flow, and is convenient for industrial production;

[0023] (3) The photocathode material provided by the present invention is used to prepare ethylene glycol, with high selectivity (ethylene glycol selectivity is 48-60%) and product amount (total amount of ethylene glycol is 102-167 mg). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a TEM image of the photocathode material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0026] The first aspect of the present invention provides a photocathode material, characterized in that the photocathode material comprises polydopamine, amorphous carbon and CdIn2S4;

[0027] The weight ratio of the polydopamine, amorphous carbon and CdIn2S4 is 1:(2-5):(5-30).

[0028] In the present invention, the photocathode material has excellent light absorption performance and catalytic carbon dioxide reduction ability, and has high selectivity for ethylene glycol.

[0029] In the present invention, when the weight ratio of the polydopamine, amorphous carbon and CdIn2S4 does not satisfy the above range, the stability of the photocathode material is poor, resulting in poor product selectivity.

[0030] Furthermore, the weight ratio of the polydopamine, amorphous carbon and CdIn2S4 is 1:(3-4):(15-20).

[0031] A second aspect of the present invention provides a method for preparing a photocathode material, wherein the method comprises the following steps:

[0032] 1) dispersing silica nanospheres and dopamine in a buffer solution for a first reaction to obtain polydopamine / silica nanospheres;

[0033] 2) annealing the polydopamine / silicon dioxide nanospheres under a protective atmosphere to obtain a sample N / C-SiO2-T;

[0034] 3) The N / C-SiO2-T is uniformly dispersed in ethylene glycol, and InCl3, CdCl2·2H2O and L-cysteine ​​are added in sequence under stirring to carry out a second reaction to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T;

[0035] 4) The CdIn2S4-N / C-SiO2-2-T solid nanospheres are subjected to a third reaction with an HF aqueous solution to obtain hollow nanospheres CdIn2S4-N / C-2-T.

[0036] According to the present invention, in step 1), the mass volume ratio of the silica nanospheres, dopamine and buffer solution is 1 g: (0.4-3) g: (150-600) mL.

[0037] According to the present invention, in step 1), the average diameter of the silica nanospheres is 50-300 nm.

[0038] According to the present invention, in step 1), the process of the first reaction includes: stirring, centrifuging, washing and drying.

[0039] According to the present invention, the stirring conditions include: time is 1-2h.

[0040] According to the present invention, the drying conditions include: temperature of 60-90° C. and time of 12-36 hours.

[0041] According to the present invention, in step 2), the annealing conditions include: temperature of 600-900° C. and time of 2-4 hours.

[0042] According to the present invention, in step 2), the protective atmosphere is selected from argon and / or nitrogen.

[0043] According to the present invention, in step 3), the mass volume ratio of the N / C-SiO2-T and ethylene glycol is 1g:(300-1000)mL.

[0044] According to the present invention, in step 3), the mass ratio of InCl3, CdCl2·2H2O and L-cysteine ​​is 1:(0.5-1):(0.5-2).

[0045] According to the present invention, in step 3), the process of the second reaction includes: reflux, centrifugation, washing and drying.

[0046] According to the present invention, the reflux conditions include: temperature of 150-200° C. and time of 0.5-3 h.

[0047] According to the present invention, the drying conditions include: temperature of 60-90° C. and time of 10-36 hours.

[0048] According to the present invention, in step 4), the mass volume ratio of the CdIn2S4-N / C-SiO2-2-T and the HF aqueous solution is 1 g: (100-500) mL.

[0049] According to the present invention, in step 4), the concentration of the HF aqueous solution is 1-7 wt %.

[0050] According to the present invention, in step 4), the process of the third reaction includes: etching, centrifugation, washing and drying.

[0051] According to the present invention, the etching conditions include: time is 12-48 hours; the drying conditions include: temperature is 60-90° C., time is 12-36 hours.

[0052] A third aspect of the present invention provides a photocathode, wherein the photocathode comprises the photocathode material according to claim 1 or a photocathode material prepared by the preparation method according to any one of claims 2-6.

[0053] In the present invention, the photocathode is prepared by dispersing the hollow nanospheres CdIn2S4-N / C-2-T in 0.5 mL of 0.5% Nafion ethanol solution, and then dropping the solution on a 1×2 cm 2 The photocathode was obtained by drying on carbon paper at 80 °C in a vacuum drying oven for 8 h.

[0054] A fourth aspect of the present invention provides use of the above-mentioned photocathode in the preparation of ethylene glycol.

[0055] A fifth aspect of the present invention provides a method for preparing ethylene glycol, wherein the method comprises:

[0056] Under light conditions, CO2 is introduced into an electrolytic cell for reaction to obtain ethylene glycol; wherein the photocathode in the electrolytic cell is the photocathode as described in claim 7.

[0057] According to the present invention, the electrolytic cell further comprises a photoanode, and the photoanode is selected from any one of BiVO4 / Ni, BiVO4 / Cu, BiVO4 / Al and BiVO4 / Ti;

[0058] According to the present invention, the electrolytic cell further comprises an electrolyte, the electrode liquid is an inorganic salt solution, and the inorganic salt solution is selected from an aqueous solution of KHCO3 and / or NaHCO3;

[0059] According to the present invention, the concentration of the inorganic salt solution is 0.05-0.2 mol / L;

[0060] According to the present invention, the voltage between the photocathode and the photoanode is 0.6-1.3V;

[0061] According to the present invention, the electrolyte of the photoanode further comprises an organic dye;

[0062] According to the present invention, the organic dye is selected from at least one of eosin Y, methylene blue, Nile red and methyl violet.

[0063] According to the present invention, the concentration of the organic dye is 1-3 mM.

[0064] The present invention will be described in detail below by way of examples. In the following examples,

[0065] The raw materials used in the examples and comparative examples are all commercially available.

[0066] Example 1

[0067] 1) dispersing silica nanospheres with an average diameter of 150 nm and dopamine in a buffer solution, stirring for 1 hour, centrifuging at 5000 rpm for 0.1 hour, washing, and vacuum drying at 60° C. for 12 hours to obtain polydopamine / silica nanospheres, wherein the mass volume ratio of silica nanospheres, dopamine and buffer solution is 1 g:1 g:200 mL;

[0068] 2) Under an argon protective atmosphere, the polydopamine / silicon dioxide nanospheres were annealed at 600° C. for 2 h to obtain a sample N / C-SiO2-T;

[0069] 3) N / C-SiO2-T was uniformly dispersed in ethylene glycol, and InCl3, CdCl2·2H2O and L-cysteine ​​were added in sequence under stirring, refluxed at 200°C for 1 h, centrifuged at 5000 rpm for 0.2 h, washed with deionized water for 3 times, and vacuum dried at 80°C for 10 h to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T, wherein the mass volume ratio of N / C-SiO2-T and ethylene glycol was 1 g:650 mL, and the mass ratio of InCl3, CdCl2·2H2O and L-cysteine ​​was 1:0.5:0.5;

[0070] 4) The CdIn2S4-N / C-SiO2-2-T solid nanospheres were etched with a 5wt% HF aqueous solution for 12 h, centrifuged at 5000 rpm for 0.2 h, washed, and vacuum dried at 80°C for 10 h to obtain hollow nanospheres CdIn2S4-N / C-2-T-1, wherein the mass volume ratio of CdIn2S4-N / C-SiO2-2-T and the HF aqueous solution was 1 g:300 mL, and the weight ratio of polydopamine, amorphous carbon and CdIn2S4 in CdIn2S4-N / C-2-T-1 was 1:3.5:18.

[0071] Figure 1 is a TEM image of the photocathode material obtained in Example 1 of the present invention, Figure 1 It can be seen that the structure of the prepared CdIn2S4-N / C-2-T-1 is hollow and circular.

[0072] Example 2

[0073] 1) dispersing silica nanospheres with an average diameter of 100 nm and dopamine in a buffer solution, stirring for 2 h, centrifuging at 5000 rpm for 0.1 h, washing, and vacuum drying at 60° C. for 24 h to obtain polydopamine / silica nanospheres, wherein the mass volume ratio of silica nanospheres, dopamine and buffer solution is 1 g:0.5 g:500 mL;

[0074] 2) Under a nitrogen atmosphere, the polydopamine / silicon dioxide nanospheres were annealed at 800° C. for 4 h to obtain a sample N / C-SiO2-T;

[0075] 3) N / C-SiO2-T was uniformly dispersed in ethylene glycol, and InCl3, CdCl2·2H2O and L-cysteine ​​were added in sequence under stirring, refluxed at 200°C for 1 h, centrifuged at 5000 rpm for 0.2 h, washed with deionized water for 3 times, and vacuum dried at 80°C for 36 h to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T, wherein the mass volume ratio of N / C-SiO2-T and ethylene glycol was 1 g:450 mL, and the mass ratio of InCl3, CdCl2·2H2O and L-cysteine ​​was 1:0.5:2;

[0076] 4) The above-mentioned CdIn2S4-N / C-SiO2-2-T solid nanospheres were etched with 4wt% HF aqueous solution for 24h, centrifuged at 5000rpm for 0.2h, washed with deionized water 3 times, and dried at 80°C for 36h to obtain hollow nanospheres CdIn2S4-N / C-2-T-2, wherein the mass volume ratio of CdIn2S4-N / C-SiO2-2-T and HF aqueous solution was 1g:200mL, and the weight ratio of polydopamine, amorphous carbon and CdIn2S4 in CdIn2S4-N / C-2-T-1 was 1:3:15.

[0077] Example 3

[0078] 1) dispersing silica nanospheres with an average diameter of 200 nm and dopamine into 300 mL of buffer solution, stirring for 1.5 h, centrifuging at 5000 rpm for 0.15 h, washing with deionized water three times, and vacuum drying at 60° C. for 24 h to obtain polydopamine / silica nanospheres, wherein the mass volume ratio of silica nanospheres, dopamine and buffer solution is 1 g:2 g:300 mL;

[0079] 2) Under an argon protective atmosphere, the polydopamine / silicon dioxide nanospheres were annealed at 700° C. for 2 h to obtain a sample N / C-SiO2-T;

[0080] 3) N / C-SiO2-T was uniformly dispersed in ethylene glycol, and InCl3, CdCl2·2H2O and L-cysteine ​​were added in sequence under stirring, refluxed at 200°C for 1 h, centrifuged at 5000 rpm for 0.2 h, washed with deionized water for 3 times, and vacuum dried at 80°C for 30 h to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T, wherein the mass volume ratio of N / C-SiO2-T and ethylene glycol was 1 g:850 mL, and the mass ratio of InCl3, CdCl2·2H2O and L-cysteine ​​was 1:0.5:1;

[0081] 4) The above-mentioned CdIn2S4-N / C-SiO2-2-T solid nanospheres were etched with 2wt% HF aqueous solution for 36 hours, centrifuged at 5000rpm for 0.2h, washed with deionized water 3 times, and dried at 80°C for 24h to obtain hollow nanospheres CdIn2S4-N / C-2-T-3, wherein the mass volume ratio of CdIn2S4-N / C-SiO2-2-T and HF aqueous solution was 1g:400mL, and the weight ratio of polydopamine, amorphous carbon and CdIn2S4 in CdIn2S4-N / C-2-T-1 was 1:4:20.

[0082] Example 4

[0083] 1) dispersing silica nanospheres with an average diameter of 50 nm and dopamine into a buffer solution, stirring for 1 h, centrifuging at 5000 rpm for 0.1 h, washing with deionized water three times, and vacuum drying at 60° C. for 24 h to obtain polydopamine / silica nanospheres, wherein the mass volume ratio of silica nanospheres, dopamine and buffer solution is 1 g:0.4 g:150 mL;

[0084] 2) Under a nitrogen atmosphere, the polydopamine / silicon dioxide nanospheres were annealed at 700° C. for 3 h to obtain a sample N / C-SiO2-T;

[0085] 3) N / C-SiO2-T was uniformly dispersed in ethylene glycol, and InCl3, CdCl2·2H2O and L-cysteine ​​were added in sequence under stirring, refluxed at 200°C for 1 h, centrifuged at 5000 rpm for 0.1 h, washed, and vacuum dried at 80°C for 24 h to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T, wherein the mass volume ratio of N / C-SiO2-T and ethylene glycol was 1 g:300 mL, and the mass ratio of InCl3, CdCl2·2H2O and L-cysteine ​​was 1:0.5:1.5;

[0086] 4) The CdIn2S4-N / C-SiO2-2-T solid nanospheres were etched with 7wt% HF aqueous solution for 16 h, centrifuged at 5000 rpm for 0.2 h, washed with deionized water three times, and vacuum dried at 80°C for 24 h to obtain hollow nanospheres CdIn2S4-N / C-2-T-4, wherein the mass volume ratio of CdIn2S4-N / C-SiO2-2-T and HF aqueous solution was 1 g:100 mL, and the weight ratio of polydopamine, amorphous carbon and CdIn2S4 in CdIn2S4-N / C-2-T-1 was 1:2:5.

[0087] Example 5

[0088] 1) dispersing silica nanospheres with an average diameter of 300 nm and dopamine into a buffer solution, stirring for 1 h, centrifuging at 5000 rpm for 0.2 h, washing with deionized water three times, and drying at 90° C. for 24 h to obtain polydopamine / silica nanospheres, wherein the mass volume ratio of silica nanospheres, dopamine and buffer solution is 1 g:3 g:600 mL;

[0089] 2) Under an argon protective atmosphere, the polydopamine / silicon dioxide nanospheres were annealed at 900° C. for 2 h to obtain a sample N / C-SiO2-T;

[0090] 3) N / C-SiO2-T was uniformly dispersed in ethylene glycol, and InCl3, CdCl2·2H2O and L-cysteine ​​were added in sequence under stirring, refluxed at 200°C for 1 h, centrifuged at 5000 rpm for 0.2 h, washed with deionized water for 3 times, and dried at 80°C for 24 h to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T, wherein the mass volume ratio of N / C-SiO2-T and ethylene glycol was 1 g:1000 mL, and the mass ratio of InCl3, CdCl2·2H2O and L-cysteine ​​was 1:0.5:1;

[0091] 4) The above-mentioned CdIn2S4-N / C-SiO2-2-T solid nanospheres were etched with 3wt% HF aqueous solution for 48h, centrifuged at 500rpm for 0.2h, washed with deionized water 3 times, and dried at 100°C for 36h to obtain hollow nanospheres CdIn2S4-N / C-2-T-5, wherein the mass volume ratio of CdIn2S4-N / C-SiO2-2-T and HF aqueous solution was 1g:500mL, and the weight ratio of polydopamine, amorphous carbon and CdIn2S4 in CdIn2S4-N / C-2-T-1 was 1:5:30.

[0092] Test Case

[0093] The photocathode materials prepared in the examples and comparative examples were tested for preparing ethylene glycol.

[0094] The photocathode was prepared as follows:

[0095] The hollow nanospheres CdIn2S4-N / C-2-T were dispersed in 0.5 mL of 0.5 wt% Nafion ethanol solution and then added dropwise to a 1×2 cm 2 The photocathode was obtained by drying on carbon paper at 80 degrees in a vacuum drying oven for 8 hours.

[0096] Ethylene glycol is prepared according to the following steps:

[0097] A photoelectrode and a cathode electrode were installed in the anode chamber and cathode chamber of a 500mL double-cell quartz photoelectrolytic cell, respectively, and 180mL of a 0.1M KHCO3 aqueous solution was added respectively. 1mM Eosin Y was added to the anode chamber, and a silicon solar cell with a voltage of 1.6V was connected to the electrodes. The voltage was adjusted to 0.4-1.2V, and CO2 was passed into the electrolytic cell under light conditions to react and obtain ethylene glycol, ethanol, acetic acid and formic acid products.

[0098] Test Example 1

[0099] BiVO4 / Ni was used as a photoanode, and an electrode comprising the photocathode material prepared in Example 1 was used as a photocathode. A silicon solar cell provided external power at a voltage of 0.8V. A photoelectrode and a cathode were installed in the anode chamber and cathode chamber of a 500mL double-cell quartz photoelectrolyzer, respectively, and 180mL of a 0.1M KHCO3 aqueous solution was added, and eosin Y was added to the anode chamber at a concentration of 1mM. The air in the water was replaced with CO2 gas for 30 minutes and the reactor was sealed. The reactor was connected to a silicon solar cell, and CO2 was continuously introduced into the reactor under light conditions for 8 hours of reaction, and the total amount of ethylene glycol organic matter reached 165mg; the ethylene glycol selectivity was 65%.

[0100] Test Example 2

[0101] The method of Test Example 1 is followed, except that the electrode comprises the photocathode material prepared in Example 2 as the photocathode, and the voltage is 0.4V.

[0102] Test Example 3

[0103] The method of Test Example 1 is followed, except that the voltage is 0.5V.

[0104] Test Example 4

[0105] The method of Test Example 1 is followed, except that the voltage is 0.6V.

[0106] Test Example 5

[0107] The method of Test Example 1 is followed, except that the voltage is 0.7V.

[0108] Test Example 6

[0109] The method of Test Example 1 is followed, except that the voltage is 0.9V.

[0110] Test Example 7

[0111] The method of Test Example 1 is followed, except that the voltage is 1V.

[0112] Test Example 8

[0113] The method of Test Example 1 is followed, except that the voltage is 1.1V.

[0114] Test Example 9

[0115] The method of Test Example 1 was followed, except that the voltage was 1.2 V and Nile red was added to the anode chamber.

[0116] Test Example 10

[0117] The method of Test Example 1 was followed, except that the voltage was 0.8 V and methyl violet was added to the anode chamber.

[0118] Test Example 11

[0119] The method of Test Example 1 is followed, except that the voltage is 0.8V.

[0120] Test conditions: The liquid products obtained in Test Example 1-11 were detected and quantified using hydrogen nuclear magnetic resonance spectroscopy.

[0121] The specific test method is: the liquid product adopts 1 HNMR analysis used 7.0395 mM DMSO D2O as the internal standard and double resonance decoupling water peak suppression technology for testing and quantitative analysis.

[0122] The results are shown in Table 1.

[0123] Table 1

[0124]

[0125]

[0126] It can be seen from Table 1 that when the photocathode prepared by the present invention is used to prepare ethylene glycol, the photocathode material has excellent light absorption performance and catalytic carbon dioxide reduction ability, and has high selectivity for ethylene glycol.

[0127] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A photocathode material, characterized in that: The photocathode material comprises polydopamine, amorphous carbon and CdIn2S4; The weight ratio of the polydopamine, amorphous carbon and CdIn2S4 is 1:(2-5):(5-30).

2. The photocathode material according to claim 1, wherein The weight ratio of the polydopamine, amorphous carbon and CdIn2S4 is 1:(3-4):(15-20).

3. A method for preparing a photocathode material, characterized in that: The method comprises the following steps: 1) dispersing silica nanospheres and dopamine in a buffer solution for a first reaction to obtain polydopamine / silica nanospheres; 2) annealing the polydopamine / silicon dioxide nanospheres under a protective atmosphere to obtain a sample N / C-SiO2-T; 3) The N / C-SiO2-T is uniformly dispersed in ethylene glycol, and InCl3, CdCl2·2H2O and L-cysteine ​​are added in sequence under stirring to carry out a second reaction to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T; 4) The CdIn2S4-N / C-SiO2-2-T solid nanospheres are subjected to a third reaction with an HF aqueous solution to obtain hollow nanospheres CdIn2S4-N / C-2-T.

4. The photocathode material according to claim 3, wherein In step 1), the mass volume ratio of the silica nanospheres, dopamine and buffer solution is 1 g: (0.4-3) g: (150-600) mL; Preferably, the average diameter of the silica nanospheres is 50-300 nm; Preferably, in step 2), the annealing conditions include: a temperature of 600-900° C. and a time of 2-4 h; Preferably, the protective atmosphere is selected from argon and / or nitrogen.

5. The photocathode material according to claim 3 or 4, wherein In step 3), the mass volume ratio of the N / C-SiO2-T and ethylene glycol is 1 g: (300-1000) mL; Preferably, the mass ratio of InCl3, CdCl2·2H2O and L-cysteine ​​is 1:(0.5-1):(0.5-2).

6. The photocathode material according to any one of claims 3 to 5, wherein: In step 4), the mass volume ratio of the CdIn2S4-N / C-SiO2-2-T and the HF aqueous solution is 1 g: (100-500) mL; Preferably, the concentration of the HF aqueous solution is 1-7 wt %.

7. A photocathode, characterized in that: The photocathode comprises the photocathode material according to claim 1 or a photocathode material prepared by the preparation method according to any one of claims 3 to 6.

8. Use of the photocathode according to claim 7 in the preparation of ethylene glycol.

9. A method for preparing ethylene glycol, characterized in that: The method comprises: Under light conditions, CO2 is introduced into an electrolytic cell for reaction to obtain ethylene glycol; wherein the photocathode in the electrolytic cell is the photocathode as described in claim 7.

10. The preparation method according to claim 9, wherein: The electrolytic cell further comprises a photoanode, wherein the photoanode is selected from any one of BiVO4 / Ni, BiVO4 / Cu, BiVO4 / Al and BiVO4 / Ti; Preferably, the electrolytic cell further comprises an electrolyte, the electrolyte is an inorganic salt solution, and the inorganic salt solution is selected from an aqueous solution of KHCO3 and / or NaHCO3; Preferably, the concentration of the inorganic salt solution is 0.05-0.2 mol / L; Preferably, the voltage between the photocathode and the photoanode is 0.6-1.3V.

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